The unusual change of permeation rate in PDMS membranes filled with crystalline calixarene and its derivative

PDMS membranes filled with crystalline calixarene (CA) and calixarene derivative (CAD) were prepared for pervaporative removal of benzene from dilute aqueous solution. With the increase of CA and CAD content, the normalized permeation rate of the filled membranes did not exhibit monotonic change, but had minimum and maximum values instead. In order to explain this unusual phenomenon, swelling experiment, XRD and PALS measurement had been carried out. A model, which describes the mass transport in the CA-filled membranes by combining swelling and crystallinity of the membranes, was proposed and validated by CAD-filled membranes. Due to the higher hydrophobicity of CAD over CA, CAD-filled PDMS membranes exhibited higher separation factor than CA-filled PDMS membranes. In addition, both CA and CAD-filled PDMS membranes showed better permselectivity than control PDMS membranes.